Pub Date : 1999-10-18DOI: 10.1109/ETFA.1999.813169
F. Balduzzi, E. Canuto, J. Proth
The paper addresses the problem of modelling and controlling manufacturing systems within the framework offered by the Manufacturing Algebra (MA). The method is outlined through a case study, including production micro- and macro-irregularities. The design of a hierarchical real time controller capable of satisfying the demand of finished products arising from an unpredictable factory planner is afforded. The dynamic model of the production process and the real time control strategies are entirely event-driven. The underlying formulation is provided by a novel discrete event state equation theory developed within MA. Control performances are proven with an event-driven simulator based on the MA, and capable of simulating in a very detailed way all the irregularities the control system has to attenuate.
{"title":"Applications of discrete-event state equations to manufacturing systems","authors":"F. Balduzzi, E. Canuto, J. Proth","doi":"10.1109/ETFA.1999.813169","DOIUrl":"https://doi.org/10.1109/ETFA.1999.813169","url":null,"abstract":"The paper addresses the problem of modelling and controlling manufacturing systems within the framework offered by the Manufacturing Algebra (MA). The method is outlined through a case study, including production micro- and macro-irregularities. The design of a hierarchical real time controller capable of satisfying the demand of finished products arising from an unpredictable factory planner is afforded. The dynamic model of the production process and the real time control strategies are entirely event-driven. The underlying formulation is provided by a novel discrete event state equation theory developed within MA. Control performances are proven with an event-driven simulator based on the MA, and capable of simulating in a very detailed way all the irregularities the control system has to attenuate.","PeriodicalId":119106,"journal":{"name":"1999 7th IEEE International Conference on Emerging Technologies and Factory Automation. Proceedings ETFA '99 (Cat. No.99TH8467)","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115003504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-10-18DOI: 10.1109/ETFA.1999.813147
H. Suwa, H. Sandoh
In manufacturing activities, reactive scheduling is effective to cope with disturbance caused by unexpected events such as machine failures. However, its performance depends on empirical knowledge by scheduling experts in many cases. The paper deals with a mathematical model of an optimal policy for periodic re-scheduling which provides an optimal re-scheduling frequency. We investigate the effectiveness of the proposed model by applying it to a jobshop scheduling problem.
{"title":"An optimal re-scheduling policy for jobshop scheduling","authors":"H. Suwa, H. Sandoh","doi":"10.1109/ETFA.1999.813147","DOIUrl":"https://doi.org/10.1109/ETFA.1999.813147","url":null,"abstract":"In manufacturing activities, reactive scheduling is effective to cope with disturbance caused by unexpected events such as machine failures. However, its performance depends on empirical knowledge by scheduling experts in many cases. The paper deals with a mathematical model of an optimal policy for periodic re-scheduling which provides an optimal re-scheduling frequency. We investigate the effectiveness of the proposed model by applying it to a jobshop scheduling problem.","PeriodicalId":119106,"journal":{"name":"1999 7th IEEE International Conference on Emerging Technologies and Factory Automation. Proceedings ETFA '99 (Cat. No.99TH8467)","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115413343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-10-18DOI: 10.1109/ETFA.1999.813080
J. Pérez, S. Felici, J. Costa
Water volumes for agriculture copes with the water scarcity (drought), which is a big problem for this sector. Agrarian Exploitations are introducing new Irrigation Systems with high technologies to prevent this problem, especially in the Mediterranean Region. An Irrigation System consists of several elements: aquifers, water pumps, a hydraulic network (pipes) and a great number of electro-values, which are far from the central post (in the order of km). to control the whole system is necessary to operate remotely every electro-value, which requires simultaneously control information (to open/close these electro-values) and power. The only way to operate with the lowest cost, is using a single wire for both, control and power. In this paper is shown a specific communication study for wide Irrigation Systems with Integrated Power Transmission, to carry out data communications over 2/spl times/1.5 mm section wires and distances no longer than 10 km, under very restrictive current consumption requirements, using OOK (On-Off Keying) modulation and a suitable filter design, both for transmission and reception.
{"title":"A specific communication study for wide irrigation systems with integrated power transmission","authors":"J. Pérez, S. Felici, J. Costa","doi":"10.1109/ETFA.1999.813080","DOIUrl":"https://doi.org/10.1109/ETFA.1999.813080","url":null,"abstract":"Water volumes for agriculture copes with the water scarcity (drought), which is a big problem for this sector. Agrarian Exploitations are introducing new Irrigation Systems with high technologies to prevent this problem, especially in the Mediterranean Region. An Irrigation System consists of several elements: aquifers, water pumps, a hydraulic network (pipes) and a great number of electro-values, which are far from the central post (in the order of km). to control the whole system is necessary to operate remotely every electro-value, which requires simultaneously control information (to open/close these electro-values) and power. The only way to operate with the lowest cost, is using a single wire for both, control and power. In this paper is shown a specific communication study for wide Irrigation Systems with Integrated Power Transmission, to carry out data communications over 2/spl times/1.5 mm section wires and distances no longer than 10 km, under very restrictive current consumption requirements, using OOK (On-Off Keying) modulation and a suitable filter design, both for transmission and reception.","PeriodicalId":119106,"journal":{"name":"1999 7th IEEE International Conference on Emerging Technologies and Factory Automation. Proceedings ETFA '99 (Cat. No.99TH8467)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116929280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-10-18DOI: 10.1109/ETFA.1999.815343
R. González, J. Cancelas, J. C. Álvarez, J. Fernández, J. Enguita
Autonomous navigation applications demand sensors with a low sample time to be able to increase speed. We have developed a stereo vision algorithm, capable to deliver dense disparity maps for single, high-resolution scanlines at high speed (40 ms/line), even for wide disparity ranges. We have tested the algorithm with synthetic and real images. Our algorithm is based on a dynamic programming schema with a cost function based on a weighted sum of squared intensify errors. Weight factors are based on gradient values. The algorithm includes explicitly detection of occlusion. Occlusion cost changes dynamically depending on gradient values of matched points.
{"title":"Fast stereo vision algorithm for robotic applications","authors":"R. González, J. Cancelas, J. C. Álvarez, J. Fernández, J. Enguita","doi":"10.1109/ETFA.1999.815343","DOIUrl":"https://doi.org/10.1109/ETFA.1999.815343","url":null,"abstract":"Autonomous navigation applications demand sensors with a low sample time to be able to increase speed. We have developed a stereo vision algorithm, capable to deliver dense disparity maps for single, high-resolution scanlines at high speed (40 ms/line), even for wide disparity ranges. We have tested the algorithm with synthetic and real images. Our algorithm is based on a dynamic programming schema with a cost function based on a weighted sum of squared intensify errors. Weight factors are based on gradient values. The algorithm includes explicitly detection of occlusion. Occlusion cost changes dynamically depending on gradient values of matched points.","PeriodicalId":119106,"journal":{"name":"1999 7th IEEE International Conference on Emerging Technologies and Factory Automation. Proceedings ETFA '99 (Cat. No.99TH8467)","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121342112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-10-18DOI: 10.1109/ETFA.1999.815363
P. Bonhomme, P. Aygaline, S. Calvez
P-time Petri nets have been developed to deal mainly with operation time constraint systems. We propose a set of reduction rules aimed at transforming the system being modeled into a simpler, but equivalent one, while preserving some properties to be analyzed. Each of these reduction rules are special cases of the corresponding rules, originally introduced by G. Berthelot (1983; 1985) for autonomous Petri nets. They preserve liveness, safeness of the underlying autonomous Petri net, in addition to timing properties (performance evaluation, live token sequences, etc.). We illustrate the use of reduction rules in order to reduce the computational complexity of scheduling problems. The problem considered consists of determining the sequence of requests to ensure the consistency of a repetitive supervision of a distributed control.
p -时间Petri网主要用于处理操作时间约束系统。我们提出了一组约简规则，旨在将被建模的系统转换为更简单但等效的系统，同时保留一些有待分析的属性。这些简化规则中的每一个都是相应规则的特殊情况，这些规则最初是由G. Berthelot (1983;1985)用于自主Petri网。除了定时属性(性能评估、实时令牌序列等)外，它们还保留了底层自治Petri网的活动性和安全性。为了降低调度问题的计算复杂度，我们举例说明了约简规则的使用。所考虑的问题包括确定请求的顺序，以确保分布式控制的重复监督的一致性。
{"title":"Transformation rules for P-time Petri nets","authors":"P. Bonhomme, P. Aygaline, S. Calvez","doi":"10.1109/ETFA.1999.815363","DOIUrl":"https://doi.org/10.1109/ETFA.1999.815363","url":null,"abstract":"P-time Petri nets have been developed to deal mainly with operation time constraint systems. We propose a set of reduction rules aimed at transforming the system being modeled into a simpler, but equivalent one, while preserving some properties to be analyzed. Each of these reduction rules are special cases of the corresponding rules, originally introduced by G. Berthelot (1983; 1985) for autonomous Petri nets. They preserve liveness, safeness of the underlying autonomous Petri net, in addition to timing properties (performance evaluation, live token sequences, etc.). We illustrate the use of reduction rules in order to reduce the computational complexity of scheduling problems. The problem considered consists of determining the sequence of requests to ensure the consistency of a repetitive supervision of a distributed control.","PeriodicalId":119106,"journal":{"name":"1999 7th IEEE International Conference on Emerging Technologies and Factory Automation. Proceedings ETFA '99 (Cat. No.99TH8467)","volume":"2675 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127485627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-10-18DOI: 10.1109/ETFA.1999.815397
C. Tarín, H. Brugger, B. Tibken, E. Hofer
We analyse the motion control module implemented on the autonomous mobile robot B21 as part of the specific software architecture developed for the SFB 527, called integration of symbolic and subsymbolic information processing in adaptive sensory-motor systems. The motion control module is first located the lowest layer of the architecture. Its functionalities are path control skill, position control skill, via-point navigation skill, and put-through skill. The interfaces to other modules and the configuration states are defined. The communication tasks are implemented independently of the functionalities in separate threads using the SMART/sup Ulm/ software frame.
{"title":"Motion control module for an autonomous mobile robot","authors":"C. Tarín, H. Brugger, B. Tibken, E. Hofer","doi":"10.1109/ETFA.1999.815397","DOIUrl":"https://doi.org/10.1109/ETFA.1999.815397","url":null,"abstract":"We analyse the motion control module implemented on the autonomous mobile robot B21 as part of the specific software architecture developed for the SFB 527, called integration of symbolic and subsymbolic information processing in adaptive sensory-motor systems. The motion control module is first located the lowest layer of the architecture. Its functionalities are path control skill, position control skill, via-point navigation skill, and put-through skill. The interfaces to other modules and the configuration states are defined. The communication tasks are implemented independently of the functionalities in separate threads using the SMART/sup Ulm/ software frame.","PeriodicalId":119106,"journal":{"name":"1999 7th IEEE International Conference on Emerging Technologies and Factory Automation. Proceedings ETFA '99 (Cat. No.99TH8467)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127528938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-10-18DOI: 10.1109/ETFA.1999.815422
O. Mohamed-Salah, A.-K. Daoud, G. Ali
An opportunistic maintenance strategy is proposed to maintain a production line consisting of k nonidentical processors and without intermediary stocks. Operational characteristics of processors are degraded with usage. In this strategy, preventive maintenance activities are combined with corrective ones as soon as a certain technical and economical conditions are satisfied. This might reduce the total number of maintenance activities and consequently the total maintenance cost incurred. Performance evaluation of a such a strategy is carried out using a simulation model.
{"title":"A simulation model for opportunistic maintenance strategies","authors":"O. Mohamed-Salah, A.-K. Daoud, G. Ali","doi":"10.1109/ETFA.1999.815422","DOIUrl":"https://doi.org/10.1109/ETFA.1999.815422","url":null,"abstract":"An opportunistic maintenance strategy is proposed to maintain a production line consisting of k nonidentical processors and without intermediary stocks. Operational characteristics of processors are degraded with usage. In this strategy, preventive maintenance activities are combined with corrective ones as soon as a certain technical and economical conditions are satisfied. This might reduce the total number of maintenance activities and consequently the total maintenance cost incurred. Performance evaluation of a such a strategy is carried out using a simulation model.","PeriodicalId":119106,"journal":{"name":"1999 7th IEEE International Conference on Emerging Technologies and Factory Automation. Proceedings ETFA '99 (Cat. No.99TH8467)","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125818442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-10-18DOI: 10.1109/ETFA.1999.815340
M. Efe, O. Kaynak
This paper presents a novel training algorithm for artificial neural networks. The algorithm combines the gradient descent technique with variable structure systems approach. The combination is performed by expressing the conventional weight update rule in continuous time and application of sliding mode control method to the gradient based training procedure. The proposed combination therefore exhibits a degree of robustness with respect to the unmodeled multivariable internal dynamics of gradient descent. With conventional training procedures, the excitation of this dynamics during a training cycle can lead to instability, which may be difficult to alleviate due to the multidimensionality of the solution space and the ambiguities on the free design parameters, such as learning rate or momentum coefficient. This paper demonstrates that a computationally intelligent system can be trained such that the adjustable parameter values are forced to settle down (parameter stabilization) while minimizing an appropriate cost function (cost optimization). The proposed approach is applied to the control of a robotic arm using feedforward neural networks.
{"title":"A hybrid training procedure for artificial neural networks leading to parametric stability and cost minimization","authors":"M. Efe, O. Kaynak","doi":"10.1109/ETFA.1999.815340","DOIUrl":"https://doi.org/10.1109/ETFA.1999.815340","url":null,"abstract":"This paper presents a novel training algorithm for artificial neural networks. The algorithm combines the gradient descent technique with variable structure systems approach. The combination is performed by expressing the conventional weight update rule in continuous time and application of sliding mode control method to the gradient based training procedure. The proposed combination therefore exhibits a degree of robustness with respect to the unmodeled multivariable internal dynamics of gradient descent. With conventional training procedures, the excitation of this dynamics during a training cycle can lead to instability, which may be difficult to alleviate due to the multidimensionality of the solution space and the ambiguities on the free design parameters, such as learning rate or momentum coefficient. This paper demonstrates that a computationally intelligent system can be trained such that the adjustable parameter values are forced to settle down (parameter stabilization) while minimizing an appropriate cost function (cost optimization). The proposed approach is applied to the control of a robotic arm using feedforward neural networks.","PeriodicalId":119106,"journal":{"name":"1999 7th IEEE International Conference on Emerging Technologies and Factory Automation. Proceedings ETFA '99 (Cat. No.99TH8467)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115462441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-10-18DOI: 10.1109/ETFA.1999.815344
L. Bergasa, M. Mazo, A. Gardel, J.C. Garcia, Á. Ortuño, A.E. Mendez
This paper shows a guidance system for an electrical wheelchair for handicapped people by head movements. A color face tracking system has been developed in order to compute head movements of the user and, depending on them, some commands are generated to drive the wheelchair. The system is non-intrusive and it allows visibility and freedom of head movements. It is able to learn the face features of the user in an automatic initial setup, working even for people of different races. It is adaptive and, therefore, robust to light and background changes in inside environments. It has been tested with several users and some results are given.
{"title":"Guidance of a wheelchair for handicapped people by face tracking","authors":"L. Bergasa, M. Mazo, A. Gardel, J.C. Garcia, Á. Ortuño, A.E. Mendez","doi":"10.1109/ETFA.1999.815344","DOIUrl":"https://doi.org/10.1109/ETFA.1999.815344","url":null,"abstract":"This paper shows a guidance system for an electrical wheelchair for handicapped people by head movements. A color face tracking system has been developed in order to compute head movements of the user and, depending on them, some commands are generated to drive the wheelchair. The system is non-intrusive and it allows visibility and freedom of head movements. It is able to learn the face features of the user in an automatic initial setup, working even for people of different races. It is adaptive and, therefore, robust to light and background changes in inside environments. It has been tested with several users and some results are given.","PeriodicalId":119106,"journal":{"name":"1999 7th IEEE International Conference on Emerging Technologies and Factory Automation. Proceedings ETFA '99 (Cat. No.99TH8467)","volume":"52 6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122874442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1999-10-18DOI: 10.1109/ETFA.1999.815348
H. Hassan, F. Buendía, J. Simó, G. Benet, A. Crespo
The design of complex mobile vehicle applications requires the combination of timing constrained activities with deliberate components. One of the main characteristics of the design is the flexibility. The system has to be adapted to the environment conditions and take actions depending on it. This influence is focused in the ability of the system to select the appropriate activity to be executed (depending on the available time) and to change its behaviour (depending on the environment information). The main goal of the paper is to characterise a model of tasks providing the required flexibility. The model has to be powerful enough to represent the functional and timing features of mobile robotic applications based on a behavioural architecture. Behavioural models have been largely used to represent advanced robotic systems which operate in uncertain dynamic environments combining information from several sensory sources and presenting different vehicle dynamics. The paper proposes the use of flexible tasks as a way to implement deliberative components in a behaviour architecture of a robot system and allows noteworthy run-time flexibility for introducing intelligent processes. Another important aspect considered in the paper is concerned with the relationship between the amount of time required by the tasks and the quality of the results obtained.
{"title":"A real-time model of flexible tasks for mobile robotic applications based on a behavioural architecture","authors":"H. Hassan, F. Buendía, J. Simó, G. Benet, A. Crespo","doi":"10.1109/ETFA.1999.815348","DOIUrl":"https://doi.org/10.1109/ETFA.1999.815348","url":null,"abstract":"The design of complex mobile vehicle applications requires the combination of timing constrained activities with deliberate components. One of the main characteristics of the design is the flexibility. The system has to be adapted to the environment conditions and take actions depending on it. This influence is focused in the ability of the system to select the appropriate activity to be executed (depending on the available time) and to change its behaviour (depending on the environment information). The main goal of the paper is to characterise a model of tasks providing the required flexibility. The model has to be powerful enough to represent the functional and timing features of mobile robotic applications based on a behavioural architecture. Behavioural models have been largely used to represent advanced robotic systems which operate in uncertain dynamic environments combining information from several sensory sources and presenting different vehicle dynamics. The paper proposes the use of flexible tasks as a way to implement deliberative components in a behaviour architecture of a robot system and allows noteworthy run-time flexibility for introducing intelligent processes. Another important aspect considered in the paper is concerned with the relationship between the amount of time required by the tasks and the quality of the results obtained.","PeriodicalId":119106,"journal":{"name":"1999 7th IEEE International Conference on Emerging Technologies and Factory Automation. Proceedings ETFA '99 (Cat. No.99TH8467)","volume":"170 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1999-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122072909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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